Full-scale and reduced-scale 3D RANS simulations for the case study of Livorno city (Italy)

The present paper represents a further stage of a wide research project in which ur- ban boundary layer (UBL) development was investigated by wind-tunnel (WT) tests and 3D steady RANS simulations on a reduced-scale (1:300) urban model of Quartiere La Venezia, a district of Livorno city (Italy). In the current stage, 3D steady RANS simulations were performed on a much more extensive full-scale model of Livorno, for the same reference wind directions (i.e. α = 240°, 270° and 300°) already analyzed in the previous stages. The goal of this paper is to understand to which extent the wider environment around a given urban geometry under investi- gation, included in the more extensive full-scale model as opposed to the less extensive reduced- scale model (of WT or/and CFD), may affect the wind flow patterns. A preliminary comparison between the CFD results of the much more extensive (i.e. CFD case 1) and the less extensive model (i.e. CFD case 2) of Livorno city for the reference wind direction α = 270°, showed a dis- crepancy of about 32% in terms of contour of wind speed ratio (U/Uref).